Question about modelling birdcage
As mooboots said in his comment, use the array modifier:


Create the curve of the bars and and empty
Make sure that both the empty and the origin of the curve sre in the center of the disk
Apply all eventual rotation and scale of the curve and the empty
Create an Array Modifier on the curve
In the modifier, disable Relative Offset and enable Object Offset. In the field below insert the empty. There shouldn't be any visible changes
Rotate the empty on the Z axis using a nice angle (like 5, 10 or 30 degrees) ans increase the Count slider in the modifier
Done


You can still change the curve or the angle, just remember that if you want to move them you need to always move the empty and the curve together